       :line 2
       :column 1}]
     {:output-dir "samples/hello/out"})
+
+  ;; URL example
+
+  (cljsc/build "samples/hello/src"
+    {:optimizations :none
+     :output-dir "out"
+     :output-to "out/hello.js"
+     :source-map true})
+
+  (mapped-stacktrace
+    [{:file "cljs/core.js"
+      :function "first"
+      :line 2
+      :column 1}]
+    {:output-dir "out"})
+
+  (print-mapped-stacktrace
+    [{:file "cljs/core.js"
+      :function "first"
+      :line 2
+      :column 1}]
+    {:output-dir "out"})
   )
 
 (defn- display-error

     :output-to "samples/hello/out/hello.js"
     :source-map true})

  ;; line 2 column 1
  (mapped-line-and-column
    (read-source-map "samples/hello/out/hello/core.js") 2 1)

  ;; hello.core
  (:ns (ns-info "samples/hello/out/hello/core.js"))

  (mapped-stacktrace
    [{:file "hello/core.js"
      :function "first"

      :line <integer>
      :column <integer>}*]

   :file must be a URL path (without protocol) relative to :output-dir. The
   returned mapped stacktrace will also contain :url entries to the original
   sources if it can be determined from the classpath."
  ([stacktrace] (mapped-stacktrace stacktrace nil))
  ([stacktrace opts]
    (let [read-source-map' (memoize read-source-map)
